Presoaking Treatment of Propolis Aqueous Extract Alleviates Salinity Stress in Spinach (<i>Spinacia oleracea</i> L.) Plants Grown under Calcareous Saline Soil Conditions

Abstract

Two pot experiments were conducted during the two successive seasons of 2014 and 2015 to study the effect of propolis extract at the rates 0, 6000, 7000, 8000 and 9000 ppm solution used as seed soaking to spinach seedlings on growth, yield and some chemical constituents of spinach plants (Spinacia oleracea L.) grown under saline soil conditions. The obtained results indicated that increasing the rates of propolis extract as seed soaking application increased the growth parameters of the treated plants. The best result was obtained by the middle rate (7000ppm) as seed soaking in both seasons of the study. The same trend was also observed regarding all studied chemical constituents, i.e. chlorophyll a, b and total caroteniods concentration, anthocyanine, total carbohydrates, total and reducing sugars, total free amino acid, free proline, crude protein, total indoles, total phenols, N, P and K in leaves. Moreover, soaking seeds in propolis extract before planting improved the metabolic activity of seeds through the increase in seed values from total and reducing sugar, total free amino acid, total indoles and total phenols as well as the lowest values from , total carbohydrate. Thus, the coincident application of propolis extract at (7000ppm) as seed soaking is recommended for improving growth, yield and chemical composition of spinach plants and to overcome the adverse effect of salinity conditions.